This book constitutes the refereed proceedings of the First International Conference of Abstract State Machines, B and Z, ABZ 2008, held in London, UK, in September 2008. The conference simultaneously incorporated the 15th International ASM Workshop, the 17th International Conference of Z Users and the 8th International Conference on the B Method. The 44 revised full papers presented together with 4 invited contributions were carefully reviewed and selected from numerous submissions. The conference fosters the cross-fertilization of three rigorous methods for the design and analysis of hardware and software systems - both in academia and industry - namely Abstract State Machines, B, and Z. Covering a wide range of research spanning from theoretical and methodological foundations to tool support and practical applications, the contributions are organized in topical sections on abstract state machines, B papers, Z papers, ABZ short papers, and the papers of the Verified Software Repository Network (VSR-net) workshop.